Roller or ball mill for the refining of cocoa and chocolate and the grinding of paints, enamels and the like

ABSTRACT

A mill for the refining of cocoa and chocolate and the grinding of paints, enamels and the like which consists of an outer tubular stator and an inner rotor revolvable in the stator. Forks are provided on the outer wall of the rotor for supporting rollers for rotation while permitting the rollers to be urged outwardly when the rotor turns so that the rollers ride on the inner surface of the stator. The rollers as thus supported are arranged in a spiral path along the outer wall of the rotor. The rollers are formed with separate grooves which define spiral ribs running from end to end of the rollers. The corners of the ribs are sharp and are maintained sharp by riding on the inner surface of the stator.

United States Patent Consoli Oct. 9, 1973 ROLLER 0R BALL MILL FOR THE1,736,394 11/1929 Dierker 241/161 REFINING- 0F COCOA AND CHOCOLATE2,413,793 l/l947 Sharp 241/131 X AND THE GRINDING 0F PAINTS,

ENAMELS AND THE LIKE l Claudio C. Consoli, Via Neera 39, Milan, ItalyFiled: Oct. 29, 1971 Appl. N0.: 193,648

Foreign Application Priority Data Inventor:

Field of Search 241/103, 105, 106, 241/110, 115,118, 161-163, 123, 131,228

References Cited UNITED STATES PATENTS 6/1918 Grassl 241/123 l/l95lVincent 241/118 Primary Examiner-Donald G. Kelly Att0rney-MorrisKirschstein et a1.

[57] ABSTRACT A mill for the refining of cocoa and chocolate and thegrinding of paints, enamels and the like which consists of an outertubular stator and an inner rotor revolvable in the stator. Forks areprovided on the outer wall of the rotor for supporting rollers forrotation while permitting the rollers to be urged outwardly when therotor turns so that the rollers ride on the inner surface of the stator.The rollers as thus supported are arranged in a spiral path along theouter wall of the rotor. The rollers are formed with separate grooveswhich define spiral ribs running from end to end of the rollers. Thecorners of the ribs are sharp and are maintained sharp by riding on theinner surface of the stator.

5 Claims, 4 Drawing Figures ROLLER OR BALL MILL FOR THE REFINING OFCOCOA AND CHOCOLATE AND THE GRINDING OF PAINTS, ENAMELS AND THE LIKECROSS REFERENCE TO RELATED APPLICATION This application is animprovement over copending application Ser. No. 81072 filed Oct. 15,1970 by Claudio Consoli for Ball or Roller Mill for the Refining ofCocoa, Chocolate, and the Grinding of Paints, Lacquers, Enamels and theLike, now US. Pat. No. 3,709,442 granted Jan. 9, 1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention Roller mill forrefining and grinding.

2. Description of the Prior Art A ball or roller mill is described andshown in the above patent, which consists of an inner rotor, and of an,outer tubular stator, between which confronting surfaces, e.g.,spirally extending channels are provided for the accommodation of ballsor rollers, which are thereby guided across a well defined path. Thematerial to be comrninuted ,is forced along such spiral path, wherebysuccessful results can be obtained, owing to rolling action of rollersor balls, conveyed by the rotor and urged into contact with the statorinner wall.

The thus designed machine has proved to be highly efficient and adequatein its performance, since the grinding fineness or final particle size.can be controlled not only by varying the processing time of material inthe mill (i.e., acting on the pump by which same material is fed), butalso be adjusting the RPM of the rotor.

As regard to the ball embodiment form of such mill, the same has beenproved particularly suitable 'for harder products (owing to smallgrinding surfaces) and at any rate hardly capable of being furtherimproved, in view of the shape of the grinding bodies.

As to the embodiment of such form wherein rollers are provided asgrinding bodies, it is to be remembered that rollers having a smoothrolling surface are foreseen for the use in the said Patent.

Now, many experimental tests, performed in particular on rather softmaterials, as, e.g., chocolate, with which the use of rollers, insteadof balls, is more suitable, owing to larger contact surface betweengrinding bodies and product, and thus due to lower specific pressure,have made manifest that the best milling effect takes place around thecorners, i.e., adjacent to front sides of rollers, and that the sharperthe corners are, the more efficient is the action of rollers.

SUMMARY OF THE INVENTION 1. Purposes of the Invention It is an object ofthe invention to provide a mill of the character described employingrollers of such configuration that a better milling effect is obtainedon soft materials such, for instance, as chocolate. I

It is another object of the invention to provide a mill of the characterdescribed in which the rollers are provided with spiral grooves betweenwhich spiral ribs are defined that extend from end to end of therollers.

It is another object of the invention to provide a mill of the characterdescribed in which the corners of the ribs are sharp and ride on theinner surface of the stator, the rollers being so mounted as to permitradially outward movement into contact with said surface so that thecorners of the ribs are self-sharpening.

2. Brief Description of the Invention The mill of the present inventionconstitutes an outer tubular stator within which an inner rotor turns.The outer surface of the inner rotor supports a plurality of cradlebearings, i.e., forks, having open ends facing the stator. These forksare mutually arranged so as to define a spiral on the rotor. The forksare provided in pairs, the forks of each pair being registered parallelto the axis of rotation of the rotor. Each pair of forks rotatablyreceives journals at the opposite ends of a different roller so that therollers like the pairs of forks are located in a spiral path extendingalong the rotor. Becuase the cradles have open end facings in thestator, the rollers are impelled outwardly as the rotor turns so thatthey ride on the inner surface of the stator. Individual rollers areprovided with a spiral groove which defines a spiral rib. The corners ofthe ribs are sharp. Because the rollers ride on the inner surface of thestator as the rollers turn, as the rollers wear down the ribs areselfsharpened. The grooves may be either rectangular or trapezoidal intheir form.

The invention now will be disclosed in the following description of twoembodiments thereof.

In the accompanying drawings in which are shown various possibleembodiments of the invention:

FIG. 1 is a front view of a few rollers;

FIG. 2 is a view taken on the line IllI of FIG. 1;

FIG. 3 is a cross-section of rollers, taken perpendicular to therotation axis of the rotor and of the rollers;

and

FIG. 4 is an enlarged fragmentary sectional view of the roller andassociated portion of the stator illustrat ing a modified form of theinvention.

Referring now to the drawings, it is to be pointed out, first of all,that the parts and components similar or equivalent to those of saidpatent are denoted by the same reference numerals, while the componentsmodified according to this patent are indicated by other referencenumerals.

Thus, restricting the description to modified components only, denotesthe rollers formed according to the present invention and guided betweenthe supporting and guiding means, extending from the outer wall of rotor4, which rotor turns in a stator S, and by which the spiral paths of therollers and of material being ground are defined. Such rollers areformed with spirally extending grooves 15, having a rectangularcrosssection, and providing two sharp corners 15a. A plurality of suchsharp comers is therefore present on the surface at each edge of theribs defined by the grooves.

Alternatively, the grooves may have a trapezoid shaped cross-section asshown in FIG. 4, with an angle of inclination adjusted according tohardness of materials to be comminuted.

As previously stated, the grinding efficiency is materially increased,and is uniformly maintained on the same high level unitl the threads areworn out.

Similarly to said patent, each roller is supported through their hubs 6aby forks 5, formed with suitable seats 5a, and from which it can beremoved, when worn out, and replaced with a new roller. The forks permitthe spirally ribbed rollers to shift radially outwardly into contactwith the inner surface of the outer tubular .stator as the rollers turnso that the ribs of the rollers ride on said surface of the statorwhereby to provide a self-sharpening action for the corners of the ribs.

Besides, the mode of operation of mill is wholly similar to that alreadydescribed in the said patent, whereby a description thereof may bedispensed with, as it has been made for the components which are notsignificant for a good understanding of the present innovation.

Finally, it is to be added that, owing to higher grinding capacity ofrollers designed as previously stated, the mill can be installed notonly in a vertical position, but in any other position that might appearmore convenient, and in particular in a horizontal position, wherein nochanges occur in its operation, also due to the fact that recourse maybe made to a forced feeding of material, whereby it can be abstainedfrom the force of gravity.

1 claim:

1. A roller mill for the refining of cocoa and chocolate and for thegrinding of paints, varnishes, enamels, and the like, said millcomprising an outer tubular stator, a tubular rotor turning inside ofsaid stator, a plurality of bearing means on the external surface of therotor, said bearing means defining a spiral path extending along theouter wall of the rotor, a plurality of rollers each associated with adifferent bearing means, said rollers having circumferential grooves,said grooves defining ribs with a smooth exterior surface the corners ofthe ribs being sharp, said bearing means being constructed to permit therollers to shift radially outwardly when the roller turns intoengagement with the inner surface of the stator so that the ribs of therollers ride on said surface of the stator whereby to provide aselfsharpening action for said corners of the ribs as the ribs weardown.

2. A mill according to claim 1, wherein the grooves extend spirally ofthe rollers.

3. A mill according to claim 2 wherein the grooves extend spirally fromend to end of the rollers.

4. A mill according to claim 1, wherein the grooves have a rectangularcross-section.

5. A mill according to claim 1, wherein the grooves show a trapezoidalcross-section.

1. A roller mill for the refining of cocoa and chocolate and for thegrinding of paints, varnishes, enamels, and the like, said millcomprising an outer tubular stator, a tubular rotor turning inside ofsaid stator, a plurality of bearing means on the external surface of therotor, said bearing means defining a spiral path extending along theouter wall of the rotor, a plurality of rollers each associated with adifferent bearing means, said rollers having circumferential grooves,said grooves defining ribs with a smooth exterior surface, the cornersof the ribs being sharp, said bearing means being constructed to permitthe rollers to shift radially outwardly when the roller turns intoengagement with the inner surface of the stator so that the ribs of therollers ride on said surface of the stator whereby to provide aself-sharpening action for said corners of the ribs as the ribs weardown.
 2. A mill according to claim 1, wherein the grooves extendspirally of the rollers.
 3. A mill according to claim 2 wherein thegrooves extend spirally from end to end of the rollers.
 4. A millaccording to claim 1, wherein the grooves have a rectangularcross-section.
 5. A mill according to claim 1, wherein the grooves showa trapezoidal cross-section.